The present invention relates to improvements of a fluid flow regulator incorporating a stepping motor or the like as a driving source for opening/closing a valve.
As flow regulators for a refrigerant in a refrigerator or an air conditioner, one using a solenoid valve or one using a needle valve are well known.
However, the flow regulator using a solenoid valve generally effects the setting of either opening or closing, and is not suitable for fine regulation of the flow rate. In addition, large noise is made when the valve is opened or closed. Further, when the solenoid valve is in either an open or a closed state, the solenoid valve needs to be set in an energized state to maintain that state, so that there is a problem in terms of power consumption as well.
On the other hand, in the case of the flow regulator using a needle valve, the flow rate of a fluid is controlled by using a stepping motor or the like as a driving source, and by converting the rotational force of the stepping motor using the thrust of the needle valve. As compared with the apparatus using the solenoid valve, the problem of the operating noise is small, and it is possible to finely regulate the flow rate.
However, with many flow regulators using the needle valve, the size of the motor as a driving source is generally large. Conceivably, this is mainly due to the fact that many of these apparatuses are used for controlling the flow rate of a refrigerant in air conditioners or the like. Namely, in the case of the air conditioner, since the pressure difference between the inlet side of the refrigerant and the outlet side thereof when the refrigerant is interrupted, it is necessary to move the needle valve with large thrust. Consequently, the size of the motor inevitably becomes large for driving the valve.
However, if the apparatus using the needle valve is used as it is as the apparatus for controlling the flow rate of a refrigerant in a refrigerator or the like, there is a problem in terms of space. In the case of the refrigerator, various compartment parts are required to be as small as possible to provide a large space for a food compartment. Accordingly, the flow regulator for the refrigerant is also naturally required to be as compact as possible. Nevertheless, if the motor size is reduced, a problem arises in that torque necessary for effecting reliable flow-rate control cannot be obtained.
Further, with the needle valve, the positional relationship between the central axis of the needle valve in a moving direction thereof and the central axis of a channel into which the needle valve is inserted, among others, is subtle so as to effect control with high accuracy. Therefore, there is another problem in that highly accurate design techniques and experiential know-how during assembly are required.
Accordingly, an object of the invention is to provide a fluid flow regulator which is simple in structure and compact, which makes it possible to effect reliable flow-rate control of a fluid, and which produces practically no operating noise during control.
In order to achieve the above object, according to the present invention, as the carriage is moved in a direction toward the fluid outlet port of the main body by the driving source, the spherical face of the sphere held in the carriage is brought into contact with the fluid outlet port provided in the main body so as to set the fluid outlet port in a closed state. Meanwhile, as the carriage is moved away from the fluid outlet port, the spherical face of the sphere is set in a state of non-contact with respect to the fluid outlet port so as to set the fluid outlet port in an open state. Accordingly, it is possible to effect reliable flow regulation control (particularly, control for stopping or allowing the flow of a fluid) with a simple structure.
In addition, since the opening/closing of the fluid outlet port are effected by the spherical face of the sphere, no subtle adjustment is required such as positioning the tip of the needle valve and the central axis of the fluid outlet port coaxially as in the case of the needle valve, so that the adjusting operation during assembling can be alleviated, thereby improving the productivity.